christmas dinner in Munich

Many restaurants are closed on Christmas Day.. Check TripAdvisor for suggestions and then check the restaurant's website for closings.
Most hotel restaurants will be open, but some will only serve their hotel guests.

I would start searching now online, as anywhere that is open on Christmas Day may well book out early.

i should have made it clearer.... looking for dinner ideas on the 24th ... as i understand it, that is when bavaria celebrates christmas...

The 24th is even more difficult. Once again, let me suggest that you look for restaurants on TripAdvisor and check to see if one or the other will be open.

The Munich tourist office may have a list of restaurants open for Christmas dinner on the 24th -- I got a similar list from Salzburg. For Salzburg they were expensive and EARLY -- many more like lunch hours. Burger King looks to be open all day, though.

You are going to have some problems with dinner at anytime on the 24th or 25th. We (7 of us) spent Christmas in Munich two years ago. We were aware of the restaurant problem for Christmas so we rented an apartment for our stay, Around noon on the 24th everything began shutting down especially the Christmas markets and same for many of the restaurants. By design we had a late lunch around 3pm and that restaurant closed at 6pm. We hit a local grocery and planned Christmas eve and day dinner for the apartment. On Christmas day all we saw that was open were the beer halls and they were packed. The beer halls were jammed with huge family groups ranging from babies to great grandparents. All with their liters of beer and bands. We joined them for the afternoon. It was lot of fun as you are all sitting at long tables with lots of toasting. I don't think you will find a quiet family restaurant open on Christmas day.